Checking brake booster - AR43.10-P-0325SX

MODEL 216.### 1#

MODEL 221.### 1#

Fig 1: Checking Brake Booster

Courtesy of MERCEDES-BENZ USA

MODIFICATION NOTES

29.7.09	Value changed: Bleed screw to brake caliper		*BA42.10-P-1001-10M
	Value changed: Bleed screw to brake caliper	Model 216 except 216.377/379 Model 221 except model 221.077/177/179	*BA42.10-P-1001-12M

	Checking
1	Operate the brake pedal several times when the engine is switched off	Until the vacuum in the brake booster (A7/7) is reduced.
2	Connect vacuum tester (01) to brake booster (A7/7) with test connection (02)		AR43.10-P-0024-01V
		Brake booster diameter	*BE43.10-P-1001-01A
		Boost factor	*BE43.10-P-1002-01A
3	Connect pressure tester (03) with connection fitting to brake caliper	Use the correct connection fitting (pitch, taper etc.), otherwise leakage and measurement errors will occur. Front axle:
		Bleed screw to brake caliper Rear axle	*BA42.10-P-1001-10M
		Bleed screw to brake caliper	*BA42.10-P-1001-12M
4	Connect pedal force measuring instrument (04) at brake pedal
5	Start engine and by opening the throttle produce a vacuum of 0.75 to 0.80 bar	If this vacuum is not attained or it drops immediately, the seal between the brake booster (A7/7) and master brake cylinder may be damaged or the check valve (2) in the vacuum line (1) may be defective: ↓
		Check non-return valve.	AR43.10-P-0023SX
		Remove/install master brake cylinder, replace seal.	AR42.10-P-0300SX
6	Apply the specified force to the brake pedal and read off the line pressure on the pressure tester (03)	In order to cover measurement errors (incorrect force on the brake pedal, incorrect vacuum) and scatter of the measuring devices, a tolerance of ± 10 bar on the specified value is permissible. The measured value must be within the value range.
6		Brake pipe line pressure	*BE43.10-P-1003-01A
7	Detach vacuum tester (01) with test connection (02) from brake booster (A7/7)	Test connection	Fig 2
7		Vacuum tester	Fig 3
8	Detach pressure tester (03) with connection fitting from brake caliper
9	Remove pedal force meter (04)
10	Bleed brake system	Only bleed the brake caliper to which the pressure tester (03) was connected.	AR42.10-P-0010SX
	Risk of accident caused by vehicle starting off by itself when engine is running. Risk of injury caused by contusions and burns during starting procedure or when working near the engine as it is running	Secure vehicle to prevent it from moving by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
11	Check brake system for leaks		AR42.10-P-0100-01V

PNEUMATIC BRAKE BOOSTER TEST SPECIFICATIONS

Number	Designation					Model 216	Model 221
BE43.10-P-1001-01A	Brake booster dia.			-	mm	265/265	265/265
BE43.10-P-1001-01A	Brake booster dia.			-	inches	9.5/95	9.5/95
BE43.10-P-1002-01A	Boost factor					8.9	8.9
BE43.10-P-1003-01A	Brake pipe line pressure	Intake pipe vacuum	Force on brake pedal	50 N	bar	27 to 37	27 to 37
		0.75...0.8 bar		100 N	bar	47 to 65	47 to 65
				150 N	bar	75 to 90	75 to 90
				200 N	bar	98 to 121	98 to 121
				250 N	bar	114 to 138	114 to 138

FRONT AXLE BRAKE CALIPER

Number	Designation		Model 216 except model 216.374/377/379	Model 221 except model 221.074/077/174/177/179
BA42.10-P-1001-10M	Bleed screw to brake caliper	Nm	14	14

REAR AXLE BRAKE CALIPER

Number	Designation		Model 216 except 216.374/377/379	Model 216.374/377/379	Model 221 except model 221.074/077/174/177/179	Model 221.074/077/174/177/179
BA42.10-P-1001-12M	Bleed screw to brake caliper	Nm	14	23	14	23

Fig 2: Identifying Test Connection (168 589 08 63 00)

Courtesy of MERCEDES-BENZ USA

Fig 3: Identifying Vacuum Tester (201 589 13 21 00)

Courtesy of MERCEDES-BENZ USA